Regular gas in WRX

Don't know about this. I don't know about when you were in HS, but truly high performance tires with high wear ratings seems to be a recent thing (for the most part).

I've noticed that a lot of cheapie tires also tend to be the ones with harder, less-grippy rubber that tends to wear longer. It's ironic that the more expensive high performance tires don't last. So one might end up with a tire that costs twice as much and wears half as long. That being said, there seem to be some really high performance tires now that have treadwear ratings from 280 up to 400.

As an aside, when I was in to get my tire patched at a Firestone shop, I was checking out their Indy car tire display (one new and one used). At room temps, the rubber on those things was rock hard. I've been told they have to be warmed up before the rubber softens up and grips hard. I suppose those tires should get hot enough at 200 MPH. Someone said that drivers starting a race drive side to side before the green flag to get the tires warmed up.

I can't speak for cars, but I used to ride a motorcycle daily. The tires that were are true delight to run were very soft and sticky and lasted about a year. And costed about $150 each.

I believe they also use tire wraps that warm the tires up. Basically an electric blanket for the tires when the car is just sitting there.

Steve

Ah, but the HS student wasn't wearing the tires out through driving. He was burning them off with smoke shows. No point in putting high performance tires on if you're just going to roast them off.

A year for a motorcycle tire isn't doing too bad. The good ones to run (street - non-race tires) last 3000-5000 miles. And yeah - $150-$250 per tire isn't out of the question. Bikes love good tires, and they eat them up and spit them out.

I know, I know. I couldn't resist. :)

Maybe he figured he was going to do a lot of showing off and peeling rubber then? Why not get nice used tires instead of cheap new ones? Just a thought.

Oh ok! I have seen that before the races start. I always thought they were just being goofy. :)

That's true. I bought an old jeep a few years ago that had a brand new set of Yokohama Geolander tires on it. They were worn almost bald after 2 summers only. I did notice that they handled pretty well also. They are a really good off-road tire.

Nope. Those tires will even tend to "flat spot" when they get a caution flag and are still rolling. You'll see em doing it then too.

Yes but the compression applied by the Turbo of Charger makes for higher than normal pressures in the cylinders. The reason the piston chambers are backed off to a lower base compression value is just because of the higher net compression when under 'boost'.

It makes no sense to run lower octane gas because a turbo'd motor has lower base compression.

I have no experience w/ this and will accept it on the face of things.

Point being that you will need a higher octane (less likely to preignite due to heat/ high compression) in a turbo motor.

TBerk

(Getting off topic).

The language is meant to serve, not be catered to.

Communication is key and if what you meant to convey is predetonation then that is what you meant.

Use it enough and it become a 'real' word. ;])

TBerk

I found several of the threads that generated so much discussion:

Yes. However - I'm just saying that "compression ratio" refers to the physical dimensions (max combustion chamber volume : min chamber volume), and can't be altered by ambient conditions.

I never said that. I realize that forced induction raises the pressures, and makes the nasty stuff (detonation/preignition) more likely as a result.

I've seen reports that regular/mid/premium in Colorado is typically

85/87/91. I remember an old '82 Olds Cutlass Cierra manual. It said that a 2 octane point reduction would be acceptable at certain altitudes (i.e. Denver). Check out the following article:

Again - I was only stating that the "compression ratio" is a fixed number determined by the physical dimensions of the engine. The compression ratio of my 2004 WRX is 8.0:1, which is the same whether I'm driving in Denver or San Francisco.

You terminology for compression ratio is correct. What I had meant to say (even though I'm pretty sure you understood me the first time) is that the ultimate cylinder pressure at TDC-compression and the amount of oxygen molecules in the charge for a turbocharged car is essentially unchanged by altitude.

Normally aspirated cars, when they can't get as much air into a cylinder because the ambient pressure is reduced by altitude or temperature, can often burn lower octane fuel successfully. There is just less oxygen (and all other gasses) per cubic foot of air and that helps resist detonation and preignition. But when a turbo is introduced, the engine can then force feed the same number of molecules into the cylinder because it has a bit of extra capacity - compressed air that would have been passed out of the waste gate at sea level is sent directly to the cylinder.

So when I was only able to find 90 octane between Oklahoma and New Mexico when my WRX 2.0 turbo was fully loaded with a trailer, I was rather apprehensive. I never felt or heard any knocking, but I bet my knock sensor and ignition timing reduction equipment got a good workout.

Your brother is not likely familiar with forced-induction cars. For a normally-aspirated car tuned for 87 octane, no increase in performance will be noticeable. But, for any forced-induction car (turbocharged or supercharged), the power gains are realized by compressing the air on the intake. You need higher octane; full stop!

I agree. One thing you dont want to happen under boost, is detonation (pinging). THATS A BAD THING. Also the computer will "learn" timing curves (among other things) to different fuels. If your ever in a pinch and the only thing available is "mr econogas regular", then it will just run like hell, as the computer will be retarding the timing and cutting back the boost to compensate for the knocking (pinging). Nurse the car to a REAL gas station and pump her full of super, and let it re-learn everything again. Good luck!

Nitro,

Please learn how to inline-post so we know what you're talking about. We can't see the message that you're replying too unless you preserve the relevant parts and put your reply at the bottom.

TOTAL CROCK OF BS!!!!! No carmaker would sell an engine that will be damaged by regular gas. Otherwise their warranty claims would be unbelievable. Yes the performance MAY suffer slightly but not enough for most people to notice. Case in point- 2001 VW Passat 1.8 T. "Requires " premium but has used only 87 octane for 125000 miles. Many problems with vehicle due to VW "quality" but none that could be attributed to lower octane. Run whatever gas you want.

Well... OK. Run whatever gas you want. But knowing what pre-ignition and detonation are and knowing what they do to an engine and knowing that higher octane helps prevent these things -- leads *me* to the conclusion that running low octane in an engine designed for premium is a Really Bad Idea (tm). I won't go so far as to say that "busterb" got lucky, but... Well, scratch that: I'm going to say that "busterb" got lucky. Do a couple Google searches on "detonation" and "pre-ignition" and decide for yourself whether you want to do this to your engine. And bear in mind that knock sensors can't *predict* engine knock, only *react* to it. They *limit* the damage that prolonged knock would cause, they don't *prevent* that damage entirely.

As for the "no carmaker would sell an engine that will be damaged by regular gas [because of the expensive warranty claims]" remark: Keep in mind this implies that the engine only need last as long as the warranty. Any forced induction of an engine can lead to accelerated engine wear if not handled properly. And by "handled properly" I'm not just referring to the hardware changes, but to proper use, like running the proper type of fuel and observing proper warm-up and cool-down of the engine. Which is why dealers won't honor warranty claims on boost-enhanced cars: They have no way of knowing whether the added boost was "handled properly." So it seems likely to me that the manufacturers design their engines so that in the worst-case scenario -- where a moron owner runs 87 octane gasahol in his STi for its entire life, never warms up the engine before slamming the boost all the way to the waste gate, and frequently shuts the engine off right after a string of quarter mile runs without letting it cool down -- the knock sensors and other design features will keep the engine alive long enough that in most cases the engine will outlive its warranty. So like I wrote at the top: Run whatever gas you want. It all comes down to whether you want to take care of your car -- something "busterb" doesn't seem particularly interested in bothering with.

Just my two-cents.

- Greg Reed